Abstract: Lun-16 block sandstone oil reservoir in Ziyin oilfield of Baise basin has entered the late stage of super-high water cut,the surplus recoverable resources with water drive is decreasing and the water-flooding efficiency be- comes poor.In order to enhance the recovery ratio and de- velopment effect,cyclic flooding experiment has been worked out.The result indicates the waterflooding devel- opment effect is improved through the cyclic flooding,the oil production becomes steady,water cut drops 2.41%, and tbe recovery ratio increases 5.57%.The alternations of the water cut in depressure cycle have three stages:ris- ing,steady and undulation to have slightly drops.The produced fluids per unit pressure drop of various wells group also appear three phases:drops gradually,relative- ly steady,drops slightly.The water-injection cycle is appropriate by 4-6 months.This experimental success has great guidance for the waterflooding development effect of the sandstone oil reservoir.